I
went to an antique tractor and engine show recently, and I
have some
questions about some of the engines that I saw.The engines in question would sit there turning over
but would only fire
and pop every once in a while, yet they continued to turn.I heard them referred to
as “hit and miss”
engines.Why didn’t
they fire every
time?Why would you
want an engine to
misfire?Wouldn’t
it do more work and
run faster if it fired every time?Also
the engines seemed to run a long time on the little glass of fuel on
top.Why do today’s
engines use
so much more
fuel?Can you
explain?

They
were before my time

Dear
Before My Time;

Hit
and Miss Engines were before my time also but, yes, I can explain, as
they are very near
and dear
to my heart--as are old tractors.Please realize that at least one of the engines at
the show was built in
the 1890’s, some five to ten years before Henry Ford built his
Quadra Cycle (automobile) and is now about 110 years old.Most of the displayed engines were from the
teens, 20’s and 30’s of the last century.The engine builders of that time were just
experimenting and learning
how to make use of internal combustion principals.A lot of their knowledge was what had been
learned on the earlier steam engines, and the internal combustion
engine
was
just in its infancy--or maybe adolescence.

First,
the fuel usage.The
little glass
container on top did not have fuel in it-- it contained oil.The oil was allowed to
drip slowly to
lubricate the piston.Those
early
engines did not have an oil pan or oil pump, so a supply of oil was
positioned
higher than what it was lubricating, so that the oil could just drip
down on
what needed lubrication.Any
oil that
was not burned was allowed to just drip off--it was a “total loss”
lubrication
system.Had you
looked closer, you would
have noticed either oil lubricators like the one on top, oil cups or
grease
cups on other critical moving parts, and no way to catch the excess
lube
from
them.The
fuel, usually gasoline
or kerosene, was usually stored in a tank built into the engine base or
sometimes
in a small external fuel tank.While
the
fuel consumption was fairly low, the horsepower was much lower.A 1 1/2 horsepower hit and
miss engine weighs
in at about 150 to 300 pounds.Of
course,
it would produce the 1 ½ horsepower all day long for many years, if you
kept it
from running out of water, fuel, and oil.

The
speed of the old engines was necessarily kept low, as the pistons were
usually
made of cast iron, and balancing was crude to non-existent.Consequently, the RPM
(Revolutions Per Minute)
were kept very low to keep the engine from shaking, bouncing around,
and FLYING
APART.A 500 RPM
engine was a very fast turning
engine and still had to be staked down or have a very heavy, solid base.In comparison, today’s 10
to 20 horsepower
lawn tractor engines weigh in at about 50 to 100 pounds and usually
turn up to
3600 RPM.

Controlling
the RPM speed on the old engines was critical to keep them from
bouncing around,
shaking, and flying apart.It
is the
speed control used in the old engines that gives them the “Hit and
Miss”
name.With no work
load on them, they
would:Hit
(Pop)--Miss (Puff)--Miss
(Puff)--Miss (Puff)--Hit (Pop).This
was caused by the speed-control governor that was usually incorporated
into the flywheel.If
the speed was faster
than the governor setting, the governor mechanism would hold the
exhaust
valve
open.With the
valve open there would be
no compression, and without compression the cylinder would miss
(misfire).Once the
RPM
speed got slower, the governor setting the mechanism would allow the
exhaust valve
to open
and close normally.That
allowed
compression, and the engine would fire (hit) normally.It would continue to fire until the RPM got
faster than the governor setting, at which time the exhaust valve would
be held
open to prevent firing and keep the engine from running too fast.If there was a load on the
engine, such as when the engine was
powering a water pump, saw, feed grinder, or generator, the engine
would
fire
every time as long as the RPM did not get above the governor setting.Now you might ask why the
speed was not
controlled by the throttle. The
throttle
could not be used because they did NOT have one.A throttle would just have added complicated
machinery that could fail or get out of adjustment--plus they had not
really
refined the carburetor enough to use a throttle-valve.This was not something you really wanted in
an era when speed was usually controlled by “giddiup” and “whoa.”

One
point of interest is that many of the display engines owners at the
show have
worked on the governors on their engines to slow them down even more.There are several reasons
for this. One is so
that there is less wear on these irreplaceable antiques.Another is so that the
actual working parts
of the engine can be seen easier.Perhaps
the most important reason is to see who can get their engine to run the
slowest.Don’t ask
me why, other than it takes a very
talented operator to get these old engines to run really slow.Thank you for your
question because as I said
earlier the old engines and tractors are close to my heart.Why?Because they are so simple to work on!